Submariners are exposed to a unique range of stressors, such as cramped living conditions, lack of privacy, extended periods of isolation and confinement, lack of sunlight, and constant threat. These are in addition to those associated with the military environment. Due to the dangers of the work and potential for disastrous consequences, submariners need to be emotionally stable and possess good coping skills. Previous research on the Royal Australian Navy (RAN) Submarine Service indicated a need for further support to improve individual coping and organisational outcomes. Based on this research, current attitudes towards Submarine Service were examined, such as views on working hours, job demands, training and preparation, and being a submariner. Going one step further, this study investigated the effectiveness of a multimodal cognitive behavioural workplace stress management intervention with RAN submariners. A quasi-experimental design was employed and the eight-session intervention was conducted with operational submariners whilst they were working on shore. Work outcomes measured included job satisfaction, job performance, and sickbay attendance, and psychological outcomes examined were stress and strain symptoms, depression, anxiety, coping resources, health and general wellbeing. These outcomes were assessed through self-report both at sea and on shore. Stress symptoms, vocational strain, interpersonal strain, and role overload strain all decreased after the intervention, and use of social support as a coping resource and confidence in job performance both increased. Unfortunately, however, these changes were not sustained in the sea-going environment. These results are discussed in light of previous research, and recommendations for the organisation and for future research are outlined.